Old English dohtor, from Proto-Germanic *dokhter, earlier *dhukter (cognates: Old Saxon dohtar, Old Norse dottir, Old Frisian and Dutch dochter, German Tochter, Gothic dauhtar), from PIE *dhugheter (cognates: Sanskrit duhitar-, Avestan dugeda-, Armenian dustr, Old Church Slavonic dušti, Lithuanian dukte, Greek thygater). The common Indo-European word, lost in Celtic and Latin (Latin filia "daughter" is fem. of filius "son"). The modern spelling evolved 16c. in southern England. Daughter-in-law is attested from late 14c.